See notes for all three forms shown here as A, B and C. These may all be the same species, although in the eastern Caribbean at least there are three clear morphotypes.

This one is a form which is always lumpy, mainly purple or blue, without forming tubes. It has many relatively small exhalent apertures, and this, with its colour, distinguishes it from Form C.

The colour is a mix of purple and yellow, and the interiors of the exhalent pores are always yellow. The surface is glossy and smooth, without conical projections or spines.